Preparation and properties of electrodeposited Al-Mn alloy coating

Aluminum-manganese alloy coatings were electroplated onto carbon steel by using AlCl3 + LiAlH4 + MnCl2 organic solvent electrolyte, and the surface morphology, composition, structure, thickness, adhesion and corrosion resistance of Al-Mn alloy coatings were observed and determined. The results show that the deposited Al-Mn alloy coating is smooth and netlike. The component of manganese with atomic concentration of 3%-8% existed in the coating with Al-Mn supersaturated solid solution and formed in the structure of (200) orientation. With the increase of current density and deposition time, the thickness of coatings rises linearly, but the adhesion force of alloy coatings with the matrix decreases. The corrosion resistance of Al-Mn alloy coatings in 3.5% NaCl solution is reduced with the increase of current density, and there is a maximum for the corrosion resistance of Al-Mn alloy coating under the deposition time of 30 min. The deposition rate, adhesion force and corrosion resistance of Al-Mn alloy coating are greater than that of pure aluminum coating under the same electro-deposition condition. The optimum deposition parameters for Al-Mn alloy coatings in organic solvent electrolyte are the current density of 0.15 to 0.50A/dm2 and deposition time of 30 to 45 min.